"Antioxidant Activity of Chondroitin Sulfate" in "Chondroitin Sulfate:Structure, Role and Pharmacological Activity"

Molecules in biologica!systems often perform more than one function. Many structures have the ability to scavenge free radicals, acting in living organisms as antioxidant, although their main biologica!function is differ­ ent. During oxidative stress, the increase in concentration of these molecules seems to be a biologica!response that in synergism with the other antioxi­ dant defense systems may protect cells from oxidation. Among these struc­ tures chondroitin sulfate (CS) has increasingly focused the interest of many research groups. This chapter briefly summarizes the action of CSs in reduc­ ing molecular damage caused by free radicals and associateci oxygen reac­ tants. The chondroitin-4-sulfate exerts higher antioxidant activity than chondroitin-6-sulfate. The specific sulfation pattern seems to play a centrai role in the inhibitory activity of these molecules on free radicals, since the suggested mechanism is entrapment by chelation of those metal cations, likeFe2+ and Cu2+, that in turn, by Fenton's reaction, are responsible of reactive oxygen species (ROS) production. Chondroitin sulfate's protection on a wide variety of molecules (i.e., lipids, proteins, DNA, and so on) and in various cells from different organs is documented in several in vitro and in vivo experimental studies. Chondroitin-4-sulfate was shown to be able to reduce biologica! injury and free radical generation in severa! models of oxidative stress-induced damage in cellular cultures. Other investigations evaluated these antioxidant properties in experimental models of disease in animals and in human pathologies, especially arthritis. The antioxidant activity of es could be used in the future as therapeutic agent in pathologies where free radicals are involved.